// subPath is relative and with slashes
sbool dirOrZipContainsPath(File location, S subPath) ctex {
  if (location.isDirectory()) {
    ret new File(location, subPath).exists();
  } else if (location.isFile()) {
    ret zipFileContains_falseOnError(location, subPath);
  }
  false;
}

Began life as a copy of #1031474